Ryobi piston rings needed

[drf256]

End gap? Why do you ask?

Smarty me, I broke a piston ring so that I could clean the groove while waiting for my new rings to be delivered. New rings wrong size! uh-oh.

If you can direct me to a site that sells the package, or a complete top end, I will go that route. I haven't found that site.

Why did you take it apart in the first place?

Just run a top ring and forget about it. It’s a string trimmer, one ring should work just fine.

Ring end gap is a way of telling if you need new rings or not. Its a way of measuring wear. May of us run a single ring in chainsaws, which are generally higher output engines than that of a string trimmer.

I run a single 1.2mm thick ring often in Stihls, and husky’s used to come out of the factory with a single 1.5mm ring. The second ring does very little more than offer more cylinder friction. There is no oil in the crankcase to control, like in a 4 stroke.

 

[Al Smith]

If it's high hour the cylinder will not be perfectly round .However unless a replacement ring is worn so badly it won't seal as it "breaks" in the ring will conform to the cylinder .However it will take some time . I might add ring gap is something you check on a model A Ford not usually something you worry about on a saw engine .
I might further add about 10 years ago I modified a Stihl 038 mag and used Caber rings with the used cylinder and piston .Cutting down a 10 cord pile of oak it took me nearly all summer .Running 15 minutes at a time before those rings seated and it blows 185 PSI now and dead sticks at over 14,000 rpm .

 

[scooterbum]

If it's high hour the cylinder will not be perfectly round .However unless a replacement ring is worn so badly it won't seal as it "breaks" in the ring will conform to the cylinder .However it will take some time . I might add ring gap is something you check on a model A Ford not usually something you worry about on a saw engine .
I might further add about 10 years ago I modified a Stihl 038 mag and used Caber rings with the used cylinder and piston .Cutting down a 10 cord pile of oak it took me nearly all summer .Running 15 minutes at a time before those rings seated and it blows 185 PSI now and dead sticks at over 14,000 rpm .

So, do you recommend caber rings?

This engine has only one crank bearing, so there is the bearing, flywheel between bearing and rod, and the rod, with nothing else outboard. It is somewhat of a vibrator. I wonder if the two rings help with piston stability while in motion.

 

[scooterbum]

Why did you take it apart in the first place?

Just run a top ring and forget about it. It’s a string trimmer, one ring should work just fine.

Ring end gap is a way of telling if you need new rings or not. Its a way of measuring wear. May of us run a single ring in chainsaws, which are generally higher output engines than that of a string trimmer.

I run a single 1.2mm thick ring often in Stihls, and husky’s used to come out of the factory with a single 1.5mm ring. The second ring does very little more than offer more cylinder friction. There is no oil in the crankcase to control, like in a 4 stroke.

I had a leaking outboard cover gasket. I disassembled to take peaky look inside, and decided it could use a hone and ring job. It could. It has not seen excessive usage.

Ring end gap is 0.012".

 

[scooterbum]

This is a system machine, with whip, blower, edger and polesaw. It is an investment worth saving.

 

[Shane¹]

At this point you might as well order some rings. Caber makes a good replacement ring and at least they seem like they are the correct size. I would just order those and wait until they come in if you can wait that long

 

[scooterbum]

At this point you might as well order some rings. Caber makes a good replacement ring and at least they seem like they are the correct size. I would just order those and wait until they come in if you can wait that long

Yes, it seems the only game in town. I will wait for Al to comment on the caber rings.

Thank you so much for taking the time to research replacement rings. It is well appreciated.

 

[Shane¹]

Caber are probably one of the best rings out there. Al won't tell you not to get them because of the quality of ring I can bet on that

 

[Al Smith]

I'll just say I've used a lot of Caber rings with good success . However that being said aftermarket parts get reviews just about as wide spread as mix oil or chainsaw brands .For that matter if you have enough money you could get a set of rings from Wiseco but you'd have more money in them than the saw is worth .On that brand the only thing I've used is the circlips .

 

[Al Smith]

More on .this .If I get a "freak " ,something that either is so old or so rare parts are hard to find I relegate it to the shelf .Eventually the parts will show up .For example it took me two years to find all the parts for two Partner p-100's and over 8 to find the parts for a Stihl 042 .I've done this most of life .Try finding parts for an Indian motorcycle some time or an Oliver crawler tractor made 70 years ago .Restoration is not for the impatient .

 

[Al Smith]

Rambling on, a story .I rebuilt a McCulloch 125 by boring out the block and installing a cast iron sleeve made of grade 50 soft gray cast .Same as what Harley D used for flat head engines .The rings I turned but never finished where made of O2 tool steel but before I did the finish I found a set from Mike Acres,the guy with web site .
I found the method for making rings on a British motor cycle site .However to do this you'd need three things.The desire to do it plus the machinery to do it plus the knowledge to do it . As luck would have I had all three .Reasonably speaking nothing is impossible .BTW I made my living as an electrician not as a tool and die maker .That skill I had to learn on my own . I do okay as a hacker .

 

[scooterbum]

Thank you much, fellas.

I will order the cabers and hone the cyl, and hopefully it will run better than when new.

 

[Al Smith]

Now then .the hone .Be darned careful because that plating is very thin .It doesn't take much to grind it out then you will have a small door stop or paper weight because it's not big enough for a row boat anchor . Just saying ----

 

[scooterbum]

Now then .the hone .Be darned careful because that plating is very thin .It doesn't take much to grind it out then you will have a small door stop or paper weight because it's not big enough for a row boat anchor . Just saying ----

Are all these cyls plated, or just alum casting? This cyl is non-magnetic. I ordered an alum ozide hone. Is this correct? The next choice is silicone carbide for harder cyls.

 

[Al Smith]

I don't know of any cylinder on anything that is just plain uncoated aluminum .One a Chevy Vega they tried a plated cylnder which did not work and with low milage would eat through the plating which was substandard and chew up the cylinder .Then it bacame fill it up with oil and check the gas .The up side to that is you could fog for mosquitoes going to work . Keep in mind that was so long ago a quart of cheap motor oil was around 59 cents now 4 bucks is a deal .

 

[scooterbum]

Will the aluminum oxide hone work on this Ryobi cylinder? If not, I need to change the order I put in today.

 

[Al Smith]

Try it and see .